Liquid detergent composition

ABSTRACT

1,054,217. Detergent compositions ESSO. RESEARCH &amp; ENGINEERING CO. April 17, 1964 [June 5, 1963], No.16017/64. Heading C5D. A liquid heavy-duty detergent composition comprises a homogeneous solution of 5-20% C 12- C 22  alkane sulphonate, particularly sodium alkane sulphonate, 10-30% poly- or pyrophosphate builder, particularly tetrapotassium pyrophosphate, 1-8% sodium xylene or toluene sulphonate as hydrotrope and 40-85% water, all by weight. Potassium, ammonium and triethanolamine alkane sulphonates are less preferred. The composition may also contain sodium sulphate, anticorrosion agents such as sodium or potassium silicates, anti-redeposition agents such as carboxymethyl cellulose and its sodium salt, viscosity reducers such as ethanol or isopropanol and further detergents such as the anionics sodium lauryl or hexadecyl sulphate sodium sulphates of oxo alcohols, alkyl phenol polyether sulphates, polyether sulphates, fatty acidsoaps or alkylaryl sulphonates, and the non-ionics alkylphenol polyethenoxy compounds and fatty alkanolamides.

United States Patent 3,527,707 LIQUID DETERGENT COMPOSITION James H.McAteer, Cranford, and Joseph F. Nelson,

Westfield, NJ., assignors to 'Esso Research and Engineering Company, acorporation of Delaware No Drawing. Filed June 5, 1963, Ser. No. 285,606Int. Cl. C11d 3/065 US. Cl. 252138 6 Claims ABSTRACT OF THE DISCLOSUREThe present invention relates to novel liquid synthetic detergentcompositions. More particularly, this invention relates to built liquidalkane sulfonate detergent compositions of improved solubility havingattractive biodegradation characteristics.

It is another object of this invention to provide homogeneous builtliquid synthetic detergent compositions of increased organic andinorganic actives content.

Yet another object of this invention is to provide an inexpensivehomogeneous liquid detergent composition of high solids content whichutilizes minimal amounts of hydrotropes.

A further object of this invention is to provide synthetic liquiddetergent compositions having improved biodegradation characteristics.

These and other objects are accomplished by utilizing alkane sulfonatesas a major organic surfactant component of the built liquid detergentformulation. It has been discovered surprisingly that alkane sulfonateshave superior compatibility with conventional builders when com paredwith the extensively utilized alkylaryl sulfonates such asdodecylbenzene sulfonate. This superiority is evidenced by the fact thatsignificantly smaller amounts of hydrotrope are required to obtainhomogeneous, clear, liquid heavy-duty formulations containing amounts ofg sodium alkane sulfonate equivalent to the amounts of The convenienceafforded by built heavy-duty deterfactants. This is a consequence of thelimited solubility of the sodium salts of such anionic surfactants inthe presence of the required high concentrations of condensed phosphatebuilders. For example, sodium tetrapropylbenzene sulfonate, a commercialdetergent, has such poor solubility in the presence of required buildersthat the detergent composition must be altered by expensivemodifications to render it useful.

Various proposals have been made to overcome this serious solubilitylimitation. In one approach the sodium salt is replaced by the moresoluble, but more expensive, potassium, ammonium or triethanol aminesalts in order to obtain the requisite surfactant concentration. Analternate device is to utilize large amounts of hydrotropes, forexample, xylene sulfonates, which act as coupling agents or co-solventsfor surfactant salt. Thus, liquid formulations containing, for example,845% of dodecylbenzene sulfonate salt commonly contain as much as 5- 15hydrotrope, or expressed more commonly 60 to 100% or more of the organicsurfactant content. The hydrotrope contributes to the cost of the finalformulation but not to its detergency. Indeed, under some circumstancesthe hydrotrope may exert an adverse effect on detergency.

The class of surfactants known as alkylaryl sulfonates, examples ofwhich have been discussed above, constitute the most extensivelyutilized active surfactant in modern detergent formulations. The presentuse of these surfactants for the formulation of detergents introducesthe further disadvantages that such detergents as now constituted areresistant to biodegradation due to their branchy structure. Thecontinued increase in use of non-biodegradable synthetic detergents iscreating increasing concern on the part of public health authorities andthe general public.

It is an object of this invention to provide built liquid syntheticdetergent compositions having high water solubility.

alkylaryl sulfonates now being employed commercially. This result iscompletely unexpected in view of the fact that the water solubility ofsodium alkane sulfonates and sodium dodecylbenzene sulfonate is verynearly identical at room temperature. Sodium alkane sulfonates may alsobe utilized in the manufacture of bar soaps and solid detergents ingranular flake form. However, the instant invention is concerned onlywith the unexpected advanages obtainable from employing the sodiumalkane sulfonate in the form of a heavy duty liquid detergent.

The alkane sulfonates employed in this invention may be in various saltforms, e.g., their potassium, ammonium or triethanol amine salts. Mostpreferred are the sodium salts due to their economic advantage. Thealkane sulfonates are prepared from C to C and preferably C to Calkanes. These alkanes are preferably unbranched normal paraflins sinceexcellent yields of highly biodegradable detergents are obtained fromthe straight chain paraffin. One to two methyl side chains per moleculeare permissible but a high amount of branching is quite undersirablesince it tends to increase the detergents resistance to biodegradation.

The alkane sulfonates employed in the detergent compositions of thisinvention may be prepared by a variety of techniques. In one method thenormal paraflin feed may be reacted with sulfur dioxide and chlorinewhereby the sulfochloride initially produced is converted to the desiredalkane sulfonate by treatment with a base, e.g. NaOH. This processproduces minor amounts of organic chlorides which tend to remain in thefinal product as an undesirable impurity. Another method of producingthe desired alkane sulfonates is by the reaction of sodium bissulfitewith a straight chain alkyl halide or by addition to a normal alphaolefin. This latter process yields primary sulfonates whose properties,e.g., solubility, limit their utility as detergent components. Yetanother method for producing alkane sulfonates is by sulfoxidation ofstraight chain paraffins in the presence of ultra violet radiation.

A particularly preferred method of preparing the alkane sulfonates is bya self-sustaining sulfoxidation process. This process involves theover-all reaction after initiation, is continuously reacted with 0.2 to4.0 moles of free sulfur dioxide per mole of parafiin and 0.01 to 2.0moles of free oxygen per mole of paraflin at temperatures in the rangeof 30 to 160 F.

The alkane sulfonic acid obtained from the radiosulfoxidation orperoxide catalyzed process described above is then neutralized with anappropriate base, such as sodium or potassium hydroxide or carbonate,utilizing well-known techniques to obtain the corresponding alkanesulfonate surfactant. The resulting sulfonate salt will typicallycontain 25% of inorganic sulfate which results from the formation ofsulfuric acid in the sulfoxidation reaction.

The preparation of alkane sulfonic acid and its sodium salt via theradio-sulfoxidation process may be subject to a wide variety ofmodifications. A more detailed description of the process may be foundin copending, commonly assigned application Ser. No. 118,221, filed May15, 1961 now abandoned.

The heavy-duty liquid detergents of this invention may contain any ofthe various types of builders and other adjuvants which areconventionally found in detergent formulations. Examples of usefulbuilders include ethylene diamine tetraacetic acid salts, polyphosphatesand pyrophosphates, particularly tetrapotassium pyrophosphate.Anticorrosion agents, such as sodium or potassium silicates, may beadded to the formulation. In addition, anti-redeposition agents, such assodium carboxymethyl cellulose may be present in the formulation. Theformulation may also contain viscosity reducers, such as ethanol orisopropanol. Various optical bleaches, perfumes, dyes or other coloringagents may also be added. In addition, the formulation may at timescontain other detergents in combination with the alkane sulfonate whenspecific results are desired. For example, sodium alcohol sulfates suchas sodium lauryl sulfate, sodium hexadecyl sulfate or sodium sulfates ofoxo alcohols may be added to the formulation.

The relative amounts of each component in the liquid detergentformulation may vary over broad limits. A typical detergent formulationmay contain from to 20, preferably 5 to 15, and more preferably to partsby weight of the alkane sulfonate per 100 parts of solution of thesulfonate surfactant as well as 0 to 5 parts of the inorganic sulfateproduced concurrently with the sulfonate. In addition, the formulationman contain from 5 to 25 parts by weight of building agent, such as acondensed phosphate, 1 to 5 parts by weight of an anticorrosion agent,such as a metasilicate, and 0.2 to 1.0 part of an anti-redepositionagent, such as sodium carboxymethyl cellulose. A viscosity reducer suchas isopropanol may be present in amounts varying from 0 to 10 parts byweight per 100 parts of solution.

The weight ratio of sulfonate surfactant to the other components of theliquid detergent formulation may similarly vary over Wide ranges.Typically the composition may contain 0.5 to 4 and preferably 1 to 3parts by weight of condensed phosphate builders per part of sulfonatesurfactant; 0.2 to 0.5 and preferably 0.3 to 0.4 part per part of ananticorrosion agent, 0.02 to 0.10 part per part of anti-redepositionagent, and 0 to 1 part per part of a viscosity reducing agent.

A particularly preferred detergent composition, based on 100 parts ofsolution, consists of 10 to 15 parts of sodium alkane sulfonate as wellas O to 3 parts of the sodium sulfate. In addition, the formulationcontains 10 to 30, preferably to 25, parts of tetrapotassiumpyrophosphate. Optionally there may also be present 2 to 4 parts, of asilicate, e.g., sodium metasilicate, 0.1 to 0.8 part of carboxymethylcellulose, and also 2 to 5 parts of isopropyl alcohol.

Ideally, a liquid detergent composition combines a high solids contentconsisting of both organic surfactant and inorganic builder in a clear,homogeneous solution. It is essential that all of the ingredients in theformulation are fully solubilized since otherwise they will settle outand their utility and appeal as detergents will be lost. As mentionedearlier in this specification, the solids content of detergentformulations is conventionally increased by employing coupling orsolubilizing agents known as hydrotropes. These materials function toincrease the maximum solids content of the formulation but also increasethe cost. It is a surprising feature of this invention that althoughconventional hydrotropes, such as sodium xylene and toluene sulfonates,are utilized in the novel formulations claimed herein, experimental dataindicate that the amounts of these materials may be reduced by as muchas 75% as compared to amounts utilized in alkylaryl sulfonate liquiddetergents of a similar solids content.

In a preferred embodiment sodium xylene sulfonate is utilized in limitedamounts as a hydrotrope for the sodium alkane sulfonate liquid detergentformulation. It has been discovered that as low as 1 part (by weight)per parts of solution will completely solubilize over 30 parts of solidsodium alkane sulfonate surfactant and builder.

Although the amount of hydrotrope needed for complete solubilization ofthe alkane sulfonate detergent is a complex function of the ratio oforganic surfactant to builders and the total solids content andtherefore is not capable of definition with exact certainty, it has beendetermined that the amount of hydrotrope needed is, at all points,significantly lower than would be expected in view of the vastexperience with commercial alkylaryl formulations. Hence, utilizing anoptimum ratio of about 2 parts of pyrophosphate builder per part ofalkane sul fonate surfactant the amount of hydrotrope needed per 100parts of detergent solution will vary from 1 to 8 as the total solidslevel varies from about 35 to 55 parts per 100 parts of solution.Expressed in other terms the amount of hydrotrope present in thedetergent formulation will be 10 to 50 weight percent of the sodiumalkane sulfonate in the formulation. It is to be understood that theamount of hydrotrope needed will increase as the total solids levelincreases and that therefore the maximum and minimum amounts specifiedare utilized with the maximum and minimum solids content respectively.

The invention may be further understood by reference to the followingexamples.

EXAMPLE 1 A series of detergent formulations was prepared in order todetermine solubility limits of the solid surfactants in liquidcompositions. All data are in terms of parts by weight per 100 parts ofsolution. The formulations are tabulated below.

1 Average carbon number: range= 013-026.

Formula I, containing sodium alkane sulfonate, was a clear, homogeneoussolution although it contained only 1% of the sodium xylene sulfonatehydrotrope. Formula II which differs from Formula I in that commercialtetrapropylene benzene sulfonate is utilized in similar proportionscontained in soluble solids. Formula III is similar to Formula II exceptfor the large increase in the hydrotrope concentration and yet wasnonetheless an opaque solution.

These results indicate the striking increase in compatibility of thesodium alkane sulfonate formulation as compared to commercial alkylbenzene sulfonate formulations. The results further show the decrease inhydrotrope utilization realized with the alkane sulfonate formulation.

EXAMPLE 2 A series of detergent formulations was prepared simrlar toExample 1 except that a much higher proportion of SOlldS was employed inthe solutions. As before, all

compositions are shown as parts by weight per 100 parts by weight ofsolution. The sodium alkane sulfonate employed had an average carbonnumber of 15. The formulations are tabulated below.

Tetrapro- Tetra- Sodium pylene potassium Sodium alkane benzenepyrophosxylene Formula. sulfonate sulfonate phate sulfonate II- 1 0 so I7 Formula I, containing sodium alkane sulfonate, was a EXAMPLE 3 Adetergent formulation having the following composition in parts per 100parts of solution by weight was analyzed for solubility.

Sodium nonodecane sulfonate 10 Sodium sulfate 2.5 Tetrapotassiumpyrophosphate 20 Sodium xylene sulfonate l Isopropyl alcohol 2 Theresulting composition was a clear homogeneous solution of reducedviscosity indicating that the addition of a viscosity reducing agentdoes not adversely affect solubility of the sodium alkane sulfonateliquid detergent formulation.

EXAMPLE 4 A C average paraifin feed consisting of a range of C to C wassubjected to 'y radiation-initiated sulfoxidation followed by treatmentwith NaOH to yield sodium octadecane sulfonate and sodium sulfate. Thesulfonate product was then mixed in a liquid detergent composition.

Parts (-wt.)/1 00 parts (wt.) of solution:

Sodium alkane sulfonate 10 Sodium sulfate 3.0 Tetrapotassiumpyrophosphate 20 Sodium xylene sulfonate 1 The composition was a clear,homogeneous solution. Substitution of tetrapropylene benzene sulfonatein place of the alkane sulfonate gave an incompletely soluble system.

EXAMPLE 5 Parts (wt.)/100 parts (wt.) of solution Tetrapro Tetrapo-Sodium Sodium pylene tassium dimethyl 1 octadebenzene pyrophosbenzeneIsopropyl cane sulfonate phate sulfonate alcohol sulfonate S1- 0 2D 5 5S2. 0 10 20 5 5 1 High concentration used to solubilize tetrapropylbenzene sulfonate active.

The results of the laundering test are tabulated below.

Increase in Percent Reflectance of Cloth After Laundering LiquidFormulation, wt. percent 0.2 0.4

Water hardness, grJgal. 2 15 2 15 S1- 11. 31 6.75 16. 3s 14. 75 S2 16.44 6. 00 16.25 15.31

The results indicate that the built sodium alkane sulfonate detergentsare comparable to the commercially known tetrapropylene benzenesulfonate detergents. The excess hydrotrope utilized in the alkanesulfonate detergent had no beneficial eifect on the detergency valuessince hydrotropes do not improve laundering ability, per se.

EXAMPLE 6 Percent dis- Percent disappearance appearance of surfactantsurfactant molecules fragments Tetrapropylene benzene sulfonate 0 0Sodium octadecane sulfonate 100 76 (Substantially linear olefin based)alkyl benzene sulfonate 94 69 The results indicate the completesuperiority of the alkane sulfonate detergents. Even when compared withalkyl benzene sulfonates based on fairly linear olefins, the alkanesulfonates show a superiority.

The advantages gained by the use of alkane sulfonates in liquidheavy-duty formulations are not restricted to those containing them asthe sole surfactant. Thus the sodium alkane sulfonates are compatiblewith nonionic and anionic surfactants employed for the production ofliquid heavy-duty detergents. These include, but are not limited to:alkylphenol polyethenoxy nonionics, alkylphenol polyether sulfates,polyethenoxy nonionics, polyether sulfates, fatty acid soaps, alkylarylsulfonates and acid amino-alcohol condensation products.

Although the present invention has been described with reference toparticular embodiments and examples it will be apparent to those skilledin the art that variations and modifications can be substituted thereforwithout departing from the true spirit of the invention which is limitedonly by the appended claims.

What is claimed is:

1. A liquid detergent composition consisting essentially of ahomogeneous solution of 5 to 20 wt. percent of a C to C sodium alkanesulfonate, 10 to 30 wt. percent of a condensed phosphate selected fromthe group consisting of polyphosphate salts and pyrophosphate salts, 1to 8 wt. percent of a hydrotrope selected from the group consisting ofsodium xylene sulfonate and sodium toluene sulfonate and 40 to 85 wt.percent water.

2. A liquid detergent composition consisting of a homogeneous solutionof 5 to 15 wt. percent of a C to C sodium alkane sulfonate, 10 to 30 Wt.percent of tetrapotassium pyrophosphate, up to 5 wt. percent sodiumsulfate, 1 to 8 wt. percent sodium xylene sulfonate and 40 to 80 wt.percent water.

3. The composition of claim 1 wherein tetrapotassium pyrophosphate isthe condensed phosphate builder and the sodium alkane sulfonate presentis 50 wt. percent of the tetrapotassium pyrophosphate.

4. A liquid detergent composition consisting of a homogeneous solutionof 10 wt. percent of a C to C sodium alkane sulfonate, 20 Wt. percent oftetrapotassium pyrophosphate, 2.5 Wt. percent sodium sulfate, 1 wt.percent sodium Xylene sulfonate, and 66.5 wt. percent water.

5. A liquid detergent composition consisting of a homogeneous solutionof 15 wt. percent of a C to C sodium alkane sulfonate, 30 wt. percent oftetrapotassium pyrophosphate, 7 wt. percent sodium Xylene sulfonate and48 wt. percent water.

6. A heavy duty liquid detergent composition consisting essentially of aphase stable solution of 5 through 20 wt. percent of sodium C to Cn-alkane sulfonate wherein the sulfo group is attached to a secondarycarbon References Cited UNITED STATES PATENTS 2,679,482 5/1954 Ross252138 2,956;026' 10/1960 Lew- 252138 2,999,068 9/1961 Pilcher et al.252-138 3,101,324 8/1963 Wixon 252138 3,085,982 4/1963 Steer et al.252137 HERBERT B. GUYNN, Primary Examiner US. Cl. X.R.

